The present invention relates to a control device for a pulse motor, and more particularly to a control device containing a microprocessor.
In recent years, pulse motors have been used in a variety of fields. For example, in a dot printer, a pulse motor is used for the paper feed and the carriage movement. In this kind of application, it is common that the pulse motor, together with other driven portions in the dot printer, for example, a print head, be controlled by a microprocessor. The phase data for the pulse motor and dot matrix pattern data for the print head are controlled by the microprocessor.
With regard to the dot printer, there has been a continuous demand to speed up the printing operation. To satisfy this demand, it is necessary that the pulse motor be operable at high speed and at a high frequency in order to minimize vibration of the motor. As described above, the pulse motor and the print head are both under the control of the microprocessor. Therefore, when the motor is speeded up, the data processing of the microprocessor is increased, which adversely influences the control provided by the microprocessor. Further, when the processing speed of the microprocessor cannot follow the high speed operation of the motor, a more sophisticated microprocessor must be used, resulting in an increase in the overall manufacturing cost. Some dot printers require an independent control for the moving speed of the carriage and the printing speed. In this type of printer, the processing program of the microprocessor is complicated, and the use of such a complicated program also prevents the pulse moter from being significantly speeded up.